Laser Irradiation of a Bio-Waste Derived Carbon Unlocks Performance Enhancement in Secondary Lithium Batteries

Pyrolyzed carbons from bio-waste sources are renewable nanomaterials for sustainable negative electrodes in Li- and Na-ion batteries. Here, carbon derived from a hazelnut shell has been obtained by hydrothermal processing of the bio-waste followed by thermal treatments and laser irradiation in liquid. A non-focused nanosecond pulsed laser source has been used to irradiate pyrolyzed carbon particles suspended in acetonitrile to modify the surface and morphology. Morphological, structural, and compositional changes have been investigated by microscopy, spectroscopy, and diffraction to compare the materials properties after thermal treatments as well as before and after the irradiation. Laser irradiation in acetonitrile induces remarkable alteration in the nanomorphology, increase in the surface area and nitrogen enrichment of the carbon surfaces. These materials alterations are beneficial for the electrochemical performance in lithium half cells as proved by galvanostatic cycling at room temperature

Mn-Doped Glass–Ceramic Bioactive (Mn-BG) Thin Film to Selectively Enhance the Bioactivity of Electrospun Fibrous Polymeric Scaffolds

In recent years, significant progress has been made in the development of new technologies to meet the demand for engineered interfaces with appropriate properties for osteochondral unit repair and regeneration. In this context, we combined two methodologies that have emerged as powerful approaches for tissue engineering application: electrospinning to fabricate a nanofibrous polymeric scaffold and pulsed laser deposition to tune and control the composition and morphology of the scaffold surface. A multi-component scaffold composed of synthetic and natural polymers was proposed to combine the biocompatibility and suitable mechanical properties of poly(D,L-lactic acid) with the hydrophilicity and cellular affinity of gelatin. As part of a biomimetic strategy for the generation of bi-functional scaffolds, we coated the electrospun fibers with a thin film of a bioactive glass–ceramic material supplemented with manganese ions. The physico-chemical properties and composition of the bi-layered scaffold were investigated, and its bioactivity, in terms of induced mineralization, was tested by incubation in a simulated body fluid buffer. The processes of the inorganic film dissolution and the calcium phosphate phases growth were followed by microscopic and spectroscopic techniques, confirming that a combination of bioactive glass–ceramics and nanofibrous scaffolds has promising potential in the regeneration of osteochondral tissue due to its ability to induce mineralization in connective tissues. © 2022 by the authors

LIPSS Applied to Wide Bandgap Semiconductors and Dielectrics: Assessment and Future Perspectives

With the aim of presenting the processes governing the Laser-Induced Periodic Surface Structures (LIPSS), its main theoretical models have been reported. More emphasis is given to those suitable for clarifying the experimental structures observed on the surface of wide bandgap semiconductors (WBS) and dielectric materials. The role played by radiation surface electromagnetic waves as well as Surface Plasmon Polaritons in determining both Low and High Spatial Frequency LIPSS is briefly discussed, together with some experimental evidence. Non-conventional techniques for LIPSS formation are concisely introduced to point out the high technical possibility of enhancing the homogeneity of surface structures as well as tuning the electronic properties driven by point defects induced in WBS. Among these, double- or multiple-fs-pulse irradiations are shown to be suitable for providing further insight into the LIPSS process together with fine control on the formed surface structures. Modifications occurring by LIPSS on surfaces of WBS and dielectrics display high potentialities for their cross-cutting technological features and wide applications in which the main surface and electronic properties can be engineered. By these assessments, the employment of such nanostructured materials in innovative devices could be envisaged

Thin coatings of biomaterials for hard tissue applications

2016 - 2017The goal of the present study is the production of new-generation coatings suitable for hard tissue implants, intended to decrease the healing time, limit infections and rejections and improve patients' life quality. Materials designed for implant coatings are mainly bioactive ceramics. Belonging to this class of biomaterials, hydroxyapatite (HAp), bioglass (BG) and glass-ceramic (BGC) are indicated for application in hard tissue replacement and regeneration. However the use of each one has strengths and weaknesses; therefore the attention has been focused on their peculiarity in the coating of metallic materials, suitable for hard tissue replacement. In particular, in order to overcome their drawback and enhance their strengths, possible solutions, like the adding of helpful component in the basic material or the choice of composites, have been investigated. The main technique used for the coatings production has been the Pulsed Laser Deposition (PLD). Furthermore the Electrophoretic Deposition (EPD) has been performed to produce composite biopolymer/bioceramic coatings, which cannot be accomplished by the conventional PLD. Hydroxyapatite has been deposited with IONPs (iron oxide nanoparticles). The IONPs have been previously obtained by the means of a really "green" technique, the PLAL (pulsed laser ablation in liquid). The obtaining of HAp/IONPs films has demonstrated how PLD is a successful deposition technique for the production of magnetic composite coatings. BG_Cu films have been also successfully deposited trough PLD and their bioactivity has been demonstrated by the hydroxyapatite growth on their surface during the soaking in simulated body fluid (SBF). The use of electrophoretic deposition (EPD) has allowed the coating of SS substrate with polymer/bioglass composite films. Also in this case a Cu-doped bioaglass has been used together with a protein-based polymer, zein, and the films bioactivity has been proved. RKKP (glass-ceramic) pulsed laser deposited has been proved functional coatings for celldelivery implantation and for the reduction of the corrosion of biodegradable implant. Although glass-ceramics show superior mechanical properties than bioglasses, they are still not enough for load-bearing application. Therefore, RKKP&C60 has been used as target for the deposition of composite films with improved hardness. Finally, RKKP has been modified by the adding of another component, manganese, useful for the bone regeneration, and its biocompatibility has been proved. [edited by author]XVI n.s

Structural and Morphological Tuning of LiCoPO4 Materials Synthesized by Solvo-Thermal Methods for Li-Cell Applications

Olivine-type lithium metal phosphates (LiMPO4) are promising cathode materials for lithium-ion batteries. LiFePO4 (LFP) is commonly used in commercial Li-ion cells but the Fe3+/Fe2+ couple can be usefully substituted with Mn3+/Mn2+, Co3+/Co2+, or Ni3+/Ni2+, in order to obtain higher redox potentials. In this communication we report a systematic analysis of the synthesis condition of LiCoPO4 (LCP) using a solvo-thermal route at low temperature, the latter being a valuable candidate to overcome the theoretical performances of LFP. In fact, LCP shows higher working potential (4.8 V vs. 3.6 V) compared to LFP and similar theoretical capacity (167 mAh·g−1). Our goal is to show the effect of the synthesis condition of the ability of LCP to reversibly cycle lithium in electrochemical cells. LCP samples have been prepared through a solvo-thermal method in aqueous-non aqueous solvent blends. Different Co2+ salts have been used to study the effect of the anion on the crystal growth as well as the effect of solution acidity, temperature and reaction time. Materials properties have been characterized by Fast-Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopies. The correlation between structure/morphology and electrochemical performances has been investigated by galvanostatic charge-discharge cycles

Substituted hydroxyapatite, glass, and glass-ceramic thin films deposited by nanosecond pulsed laser deposition (Pld) for biomedical applications: A systematic review

The deposition of thin films of bioactive materials is the most common approach to improve the bone bonding ability of an implant surface. With this purpose, several wet and plasma assisted deposition methods were proposed in the scientific literature. In this review, we considered films obtained by nanosecond Pulsed Laser Deposition (PLD). Since hydroxyapatite (HA) has composition and structure similar to that of the mineral component of the bone, the initial studies focused on the selection of experimental conditions that would allow the deposition of films that retain HA stoichiometry and crystallinity. However, biological apatite was found to be a poorly crystalline and multi-substituted mineral; consequently, the attention of researchers was oriented towards the deposition of substituted HA, glass (BG), and glass-ceramic (BGC) bioactive materials to exploit the biological relevance of foreign ions and crystallinity. In this work, after a description of the nanosecond ablation and film growth of ceramic materials, we reported studies on the mechanism of HA ablation and deposition, evidencing the peculiarities of PLD. The literature concerning the PLD of ion substituted HA, BG, and BGC was then reviewed and the performances of the coatings were discussed. We concluded by describing the advantages, limitations, and perspectives of PLD for biomedical applications

Pulsed laser deposition of thin films of TiO2 for Li-ion batteries

Microbatteries produced by physical deposition methods are expected to play a pivotal role in many different micro-electronic applications such as stand-alone sensors, implantable or wearable medical devices, radio frequency identification-based systems and smart-cards. In this study pulsed laser deposition (PLD) using a femtosecond-pulsed laser has been applied to TiO2 target materials to produce thin films of anatase-based nanoparticles on aluminum substrates suitable for application as negative electrode in Li-ion MBs. Different post-deposition treatments have been evaluated: films morphology and composition have been investigated with a multi-technique approach and the corresponding performance and electrochemical properties in Li-ion MBs have been analyzed by cyclic voltammetry and galvanostatic techniques. Compact and dense TiO2 films composed by nanoparticles were obtained by PLD with co-crystallization of both anatase and rutile phases. Post-deposition annealing at temperature of 500 °C promote the rutile to anatase phase transition. As deposited TiO2 films are electrochemically almost inactive in lithium half cells, whereas post deposition annealing (either in Ar or Air) boosts the electrochemical activity: air annealing outperforms Ar annealing. The additional deposition of a outer carbon layer by PLD on the TiO2 films further improves the Li+ transport properties, the reversibility of the electrochemical intercalation/de-intercalation reaction as well as the battery performance in terms of capacity retention upon cycling and rate response

Transition metal carbide core/shell nanoparticles by ultra-short laser ablation in liquid

Transition metal carbide nanoparticles are a class of technological interesting materials with a wide range of applications. Among metal carbides, tantalum carbides have good compatibility with the biological environment while molybdenum carbides are used as catalyst in electrochemical reactions. Laser ablation of bulk transition metal targets in some liquids is here reported and laser ablation in organic solvents is used as simple synthetic strategy for the production of carbide nanostructures. Herein, the nanoparticles produced by ultra-short laser ablation of tantalum and molybdenum in water, acetone, ethanol and toluene have been characterized by TEM, XRD and XPS analysis. The combined effect of metal and solvent chemical and physical properties on the composition of the nanomaterials obtained has been pointed out. In particular, the different reactivity of Ta and Mo with respect to oxidizing species determines the composition of particles obtained in water, on the other hand the organic solvents decomposition allows to obtain transition metal carbide (TMC) nanoparticles. The observed carbonaceous shell formed on TMC allows to protect the particle’s carbidic core and to improve and tailor the applications of these nanomaterials

Pulsed laser-deposited composite carbon–glass–ceramic films with improved hardness

A composite material obtained by mixing a glass–ceramic powder and C60 has been used to obtain thin films by nanosecond pulsed laser deposition technique, with the aim to improve the mechanical properties of the potentially bioactive coatings. Films have been deposited by using a Nd:YAG laser source (λ = 532, τ = 7 ns, 10 Hz) on titanium substrates heated at different temperatures. The deposited coatings present a sub-micron homogeneous texture completely covering the substrate with micrometric inclusions distributed on the whole surface, as observed by AFM and SEM. IR and XRD spectra of films are characteristic of amorphous calcium silicate materials, suggesting that the carbonaceous component inhibits the glass matrix crystallization, also at high deposition temperatures. Micro-Raman measurements evidence that fullerene transforms into amorphous carbon and reduced graphene oxide (RGO)-like domains in films deposited at room temperature and 500 °C, respectively. The presence of the RGO-like domains embedded in the amorphous glassy matrix has been related to the observed improved Vickers microhardness